I don't know about you, but there's something very romantic about Vietnam.
Apart from the sea and nice clam beach, you can find a secret gems of nature hidden in Mui Ne (4 hour drive from Ho Chi Minh City)
Here is White Sand Dune in Mui Ne, Vietnam.
It is really a long difficult journey from Ho Chi Minh as you need to drive 60km per hour. Therefore, it took me 4-5 hours for only 200 km. apart.
But the result is also amazing! I don't really recommend you go in the summer as the sun might burn you alive. Winter is really interesting as the wind will blow your skirt to the sky (may be if you don't be careful or if you are intended to, you can be a Marilyn Monroe there, instead of New York City)
you rent the jeep there and he will take you to the viewing spot with no limited time (However bare in mind that h will take you only two spot, therefore you need to take your time taking photo or walking by yourself to the top of the pyramid sand)